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Holy Grail of gossypol-free cottonseed nearer reality

A genetic slicing and dicing technique that greatly reduces the amount of toxic gossypol in cottonseed may be a solution to a problem that has plagued the cotton industry for decades: how to get more use from the seed without compromising the plant’s ability to fend off insects.

Keerti Rathore, a plant biotechnologist at the Institute for Plant Genomics and Biotechnology at Texas Agricultural Experiment Station, College Station, utilized a gene suppression technique that slashes gossypol levels in cotton seed but allows it to remain in leaves and other parts of the plant to help deter pests.

While cottonseed meal is widely used in cattle and dairy rations — animals with multiple stomachs have the ability to detoxify gossypol — its use for swine, poultry, and other animals has been limited because of the toxin. Ditto for humans: ingesting gossypol can cause heart and liver problems and has been shown to suppress sperm production in males (both human and livestock).

Nearly 45 million metric tons of cottonseed is produced worldwide each year; about 22 percent of that is very high quality protein. Eliminating gossypol to increase cottonseed utilization for both animal and human nutrition has long been something of a holy grail for researchers.

“The potential for gossypol-free cottonseed is huge,” one researcher said a few years ago. “If we could get rid of gossypol, we could increase by 30 percent the amount of cottonseed that could be fed to cows, and it would also open up the market for hogs and other animals that can’t handle gossypol at all.”

In the 1950s and 1960s, scientists succeeded in breeding cotton varieties with no gossypol glands, but that left the plants susceptible to insects and the varieties were a commercial flop. And while Texas A&M University’s novelty TAMUnuts snack food made from gossypol-free cotton seeds wasn’t a rousing hit either, it is estimated that 500 million people worldwide could benefit from cottonseed’s high protein content.

Rathore and his team used a powerful gene-silencing mechanism to suppress the gossypol gene in cotton seed while leaving it intact elsewhere in the plant.

The Ribonucleic Acid Interference technology discovered by U.S.-based scientists Andrew Fire and Craig Mello (for which they shared a Nobel Prize this year), has been used mostly in medical research to arrest the development of cancer and other life-threatening diseases.

“This is so overwhelming, my phone has been ringing off the wall,” Rathore said. “While we’ve been conducting the basics of this research for some time, Cotton Incorporated funding has allowed us to continue it, and we hope to move forward with more research with their continued funding.”

Roy Cantrell, vice president of research for Cotton Incorporated, said the organization, funded primarily through producer check-off contributions, has sponsored “a great deal” of gossypol research that has led to this success. “Because of this research, new food and feedstuffs markets will be open for cotton,” he says. “We’re excited for cotton producers across the U.S., because this could eventually increase the value of their cottonseed by opening new and varied food and feed markets.”